Facile and Reliable Emission‐Based Nanomolar Anion Sensing by Luminescent Iridium Receptors Featuring Chelating Halogen‐Bonding Sites

Abstract

An anion sensor is presented that combinesabidentateh ydrogen-(HB) or halogen-bonding (XB) site with a luminescent monocationic Ir fragment for strongb inding of common anions (K a up to 6 10 4 m À1)w ith diagnostice mission changes. An ew emission-based protocol for fast and reliabled etection was derived on the basis of correction for systematic but unspecificb ackground effects. Such as imple correction routine circumvents the hitherto practical limitations of systematic emission-based analysis of anion binding with validated open-source software (BindFit).T he anticipated order of K a values was obeyed according to size and ba-sicity of the anions(Cl > Br = OAc) as well as the donor atom of the receptor (XB:6 10 4 m À1 > HB:5 10 3 m À1), and led to submicromolar limitso fd etection within minutes.T he results were further validated by advanced NMR techniques, and corroborated by X-ray crystallographic dataa nd DFT analysis, which reproduced the structural and electronic features in excellent agreement. The resultss uggest that correctedemission-baseds ensingm ay become ac omplementary,r eliable, and fast tool to promote the use of XB in various application fields,d ue to the simple and fast opticald etermination at high dilution.

Halogen bonding and chalcogen bonding mediated sensing

“…The first example of a XB receptor containing the ubiquitous, luminescent cyclometallated Ir(ppy) 2 -motif 113,114 was reported by Schubert and co-workers in 2020. 115 Containing an additional 4,4-bis-iodotriazole bipy ligand, 9.XB displayed significantly enhanced Cl − binding (60 000 M −1 ) in comparison to its HB congener in ACN (5000 M −1 ). Both Br − and OAc − were also bound, albeit weaker.…”

Towards Incorporation in Larger Architectures: A Polymeric Halogen Bond‐Based Iridium Sensor

“…The main goal of this study was the development of an iridium(III) complex featuring the XB donor capability of our previously published sensors [ 20 ] while adding the possibility to attach this system to a polymer. Hence, to prove the functionalization of the complex 6 , we chose a commercially available methoxy‐poly(ethylene glycol)‐azide (PEG‐N 3 , M n = 5000 g mol −1 ) for CuAAC reaction.…”

“…However, iridium(III)‐based metal complexes gained more importance in the last years due to their advantageous properties like higher emission quantum yields [ 23,24 ] which we also demonstrated in previous studies. [ 20,21 ]…”

NPA-Cu2+ Complex as a Fluorescent Sensing Platform for the Selective and Sensitive Detection of Glyphosate

“…A desirable linear relationship was observed between the fluorescence intensity and Cu 2+ concentration, represented by y = −21.20 x + 376.29 ( R 2 = 0.99) ( Figure 2 b). The binding constant ( K 11 ) was calculated to be 1.8 × 10 4 M −1 ( Figure S8 ), which was calculated with validated open-source software (BindFit) [ 35 ]. The limit of detection (LOD) for Cu 2+ was calculated to be 0.21 μM based on the equation of LOD = 3 σ/k , where σ is the blank standard deviation and k is the slope of the fluorescence intensity ratio vs. analyte concentration plot [ 36 ].…”